Age-related macular degeneration (AMD) is the leading cause of visual loss in individuals over the age of 65, and it occurs in 30% of people over the age of 80. It impacts approximately 11 million people within the United States, and 170 million people worldwide. With the increase in life expectancies, AMD is expected to rise 40% by the year 2040, thus, it can be considered an epidemic. AMD is an intricate disease that is a result of genetic and environmental risk factors and associations. While some of these risk factors cannot be modified, other factors such as tobacco smoking, body mass index, and dietary measures may be adjusted to help slow the progression of the disease.
Importance of Lifestyle and Behaviors
To emphasize the interplay between genetic factors and behavioral factors, a study from Seddon et al. examines the onset and progression following a pair of monozygotic (identical) twins. Twin studies allow researchers to determine genetic and environmental roles, which is evidenced by the fact that monozygotic twins share 100% of their genes. As seen in Figure 1 below, twin A (on the right) has a more advanced form of AMD along every time point when compared to his co-twin B (on the left). Considering that the twins shared the same genetic makeup, this leads researchers to believe that the environment may play a considerable role in the progression of AMD. It was observed that twin A, with the more advanced AMD, was a tobacco smoker and received less of the nutrients: vitamin D, betaine, and methionine.
This research emphasizes the importance of incorporating more antioxidants in your diet stemming from fruits and dark, leafy vegetables. In addition, exercising for 20 minutes or more three times per week has been shown to decrease the risk of vision loss from AMD.
Pennington, K.L., DeAngelis, M.M. Epidemiology of age-related macular degeneration (AMD): associations with cardiovascular disease phenotypes and lipid factors. Eye and Vis 3, 34 (2016). https://doi.org/10.1186/s40662-016-0063-5
Seddon JM, Reynolds R, Shah HR, Rosner B. Smoking, dietary betaine, methionine, and vitamin D in monozygotic twins with discordant macular degeneration: epigenetic implications. Ophthalmology. 2011; 118: 1386–1394.